//Given a binary tree, determine if it is height-balanced. 
//
// For this problem, a height-balanced binary tree is defined as: 
//
// 
// a binary tree in which the left and right subtrees of every node differ in he
//ight by no more than 1. 
// 
//
// 
// Example 1: 
//
// 
//Input: root = [3,9,20,null,null,15,7]
//Output: true
// 
//
// Example 2: 
//
// 
//Input: root = [1,2,2,3,3,null,null,4,4]
//Output: false
// 
//
// Example 3: 
//
// 
//Input: root = []
//Output: true
// 
//
// 
// Constraints: 
//
// 
// The number of nodes in the tree is in the range [0, 5000]. 
// -104 <= Node.val <= 104 
// Related Topics 树 深度优先搜索 递归 
// 👍 582 👎 0


//leetcode submit region begin(Prohibit modification and deletion)
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public boolean isBalanced(TreeNode root) {
        return  judge(root) > -1;
    }
    public int judge(TreeNode root) {
        if(root == null) {
            return 0;
        }
        int leftDepth = judge(root.left);
        int rightDepth = judge(root.right);
        if(leftDepth > -1 && rightDepth > -1 && rightDepth - leftDepth <= 1 && leftDepth - rightDepth <= 1) {
            return rightDepth > leftDepth ? ++rightDepth : ++leftDepth;
        }
        return -1;
    }
}
//leetcode submit region end(Prohibit modification and deletion)
